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Availability still depends on the watch model, purchase region, paired iPhone, and software versions.
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The short version
On November 5, 2024, Apple and Masimo began a bench trial in California over trade-secret and employee-recruitment allegations. Masimo was no longer seeking its original $1.85 billion damages claim; it instead sought an injunction.
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That trial did not directly cause the blood-oxygen feature to disappear from U.S. Apple Watches. The U.S. restriction came from a separate International Trade Commission patent case. The ITC found that Apple imported watches using technology covered by Masimo patents, so Apple sold affected U.S. models with the feature disabled.
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- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
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Apple later redesigned the system so the Watch collects the optical data while the paired iPhone handles processing and displays results. Secondary reports said functionality returned for certain U.S. models with iOS 18.6.1 and watchOS 11.6.1 in August 2025. Do not assume every U.S. Apple Watch is eligible.
The Federal Circuit affirmed the original ITC ruling in March 2026, but an ITC judge separately found that Apple’s redesigned implementation did not infringe the asserted Masimo patents. The ITC later declined to review that determination.
What trial began on November 5, 2024?
The proceeding was a bench trial in California, meaning the judge—not a jury—would decide the case. Masimo alleged that Apple recruited former Masimo employees and misappropriated confidential information while developing blood-oxygen capabilities for the Apple Watch.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsThe dispute followed a 2023 jury trial that ended in a mistrial after the jury failed to reach a unanimous verdict. MacRumors reported that six of seven jurors favored Apple, while one juror did not change her position.
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Masimo originally sought $1.85 billion, royalties, lost profits, and potentially enhanced damages. For the 2024 bench trial, it abandoned the monetary claims and pursued injunctive relief instead. An injunction against Apple would not automatically mean an immediate nationwide sales ban; the effect would depend on the judge’s findings and the scope of any order.
The supplied record does not establish a final outcome for every trade-secret allegation. It should therefore not be described simply as an Apple victory or a finding that Apple “stole” Masimo’s technology.
Three Apple–Masimo disputes, not one
| Proceeding | Main issue | Practical significance |
|---|---|---|
| California trade-secret case | Alleged employee poaching and misappropriation of confidential information | The subject of the November 2024 bench trial |
| ITC patent case | Whether imported Apple Watches infringed Masimo and Cercacor pulse-oximetry patents | Led to an exclusion order and disabled blood oxygen on affected U.S. models |
| Apple’s patent case against Masimo | Whether Masimo smartwatches infringed Apple patents | A jury awarded Apple $250 in October 2024, the statutory minimum it had sought |
Keeping these cases separate is essential. A ruling in the trade-secret trial did not itself determine whether Apple could import watches under the ITC patent order.
Why U.S. Apple Watches had blood oxygen disabled
Masimo and Cercacor complained to the ITC in June 2021. An ITC administrative law judge ruled on January 10, 2023, that Apple violated Section 337 by importing watches that infringed asserted pulse-oximetry patents. The ITC subsequently issued a limited exclusion order affecting infringing Apple Watches.
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- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
Apple continued selling affected hardware in the United States after disabling the blood-oxygen function. U.S. Customs and Border Protection permitted redesigned watches to enter with the feature disabled. The dispute concerned U.S. importation and sales, so the same limitation did not necessarily apply to watches sold in other countries.
The issue was primarily one of enabled functionality and implementation—not proof that every underlying optical component had been physically removed. A watch could contain the relevant sensor hardware while its blood-oxygen software remained unavailable in the United States.
How Apple’s workaround changed the feature
In the original arrangement, the Watch measured and processed blood-oxygen data as part of the on-watch experience. In the redesigned approach described by secondary reports, the Watch still collects data using its optical hardware, but the paired iPhone performs some or all of the processing and presents the result through the Health app or related interface.
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- GET SMARTER HEALTH INSIGHTS—Apple Watch SE 3 is an advanced health tracker that helps you better understand your body. The smartwatch sends alerts for an irregular heart rhythm, or an unusually high or low heart rate.* You can view your overnight health tracking metrics with the Vitals app,* track your sleep score, and get sleep apnea notifications.*
- A GREAT FITNESS TRACKER—SE 3 can track your workouts in a healthy number of ways—from running and strength training to simply achieving your 10K steps a day. With real-time metrics and Workout Buddy powered by Apple Intelligence from your nearby iPhone,* you’ll hit your goals like never before.
- KEEP HELP CLOSE AT HAND—SE 3 is a smartwatch that can detect a hard fall or severe car crash and automatically help connect you to emergency services and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- WOMEN’S HEALTH INSIGHTS—SE 3 has advanced sensors that track your wrist temperature while you sleep. With this smartwatch, you can log your periods and symptoms, get period predictions, and get notified of cycle deviations.*
- GREAT BATTERY LIFE AND FASTER CHARGING—Enjoy a smartwatch with all-day, 18-hour battery life* from sunup to sundown. Then charge up to twice as fast as SE 2* and get up to 8 hours of battery in just 15 minutes.*
What changed after the 2024 trial began?
- September 2020: Apple introduced blood-oxygen sensing with Apple Watch Series 6.
- June 2021: Masimo filed its ITC complaint.
- January 2023: An ITC judge found Apple violated Section 337.
- Late 2023 and early 2024: Apple sold affected U.S. watches with blood oxygen disabled.
- November 2024: Apple and Masimo began the California trade-secret bench trial.
- January 2025: Masimo reported that CBP rejected one additional Apple redesign.
- August 2025: Secondary reports said Apple restored the feature on certain U.S. models through iOS 18.6.1 and watchOS 11.6.1.
- March 19, 2026: The Federal Circuit affirmed the original ITC ruling. Separately, an ITC judge found Apple’s redesigned implementation non-infringing.
- April 2026: The ITC declined to review that non-infringement determination.
The Federal Circuit decision affirmed the ruling against Apple’s earlier implementation. It did not give Apple unrestricted permission to use that original design. The favorable later finding concerns the redesigned implementation.
Sources include the Federal Circuit opinion, MacRumors’ report on the redesigned implementation, and MedTech Dive’s report on the ITC review.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is blood oxygen available on U.S. Apple Watches now?
It is available again on at least some U.S.-sold Apple Watch models, but not universally. Eligibility can depend on:
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- the country or region where it was purchased;
- the paired iPhone model;
- iOS and watchOS versions; and
- the device’s regional configuration.
The most reliable check is the device itself. Look for the Blood Oxygen app, check whether readings appear in the Health app, and confirm that both the iPhone and Watch are updated. Apple’s current support documentation should take precedence over older reports or marketplace listings.
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- A FULL-FEATURED HEALTH TRACKER—Apple Watch Series 11 gives you invaluable insights about your body, right from your wrist. Take an ECG anytime* and get alerts for a high and low heart rate or an irregular rhythm*—so you can stay closer to your heart. You can also view your overnight health tracking metrics with the Vitals app* and be notified of possible sleep apnea.*
- KNOW YOUR SLEEP SCORE—With advanced sleep tracking, Series 11 gives you a daily sleep score. It’s an easy way to help measure and understand the quality of your sleep, so you can make it more restorative.
- GET HYPERTENSION NOTIFICATIONS—Did you know that Series 11 can spot signs of chronic high blood pressure? By analyzing how your blood vessels respond to beats of the heart, it can notify you of possible hypertension.*
- SAFETY FEATURES—A smartwatch that puts your safety first. Series 11 can detect a hard fall or severe car crash, automatically help connect you with emergency services, and notify your emergency contacts.* Check In can automatically notify a loved one when you’ve arrived at your destination.
- A POWERFUL FITNESS TRACKER—With advanced metrics and motivating features like Pacer, Heart Rate Zones, training load, and Workout Buddy powered by Apple Intelligence from your nearby iPhone*—Series 11 is made to help everyone stay active, from runners and hikers to strength-training enthusiasts.
What buyers should check
Buying new
- Confirm that the exact model supports blood oxygen in your country.
- Ask the seller whether the watch is intended for your market, especially if it is imported.
- Check the required iPhone and software versions.
- Do not assume a newer model automatically has the feature.
Buying used or refurbished
- Ask for the model and regional identifier.
- Verify that the Blood Oxygen app or Health records are available before completing the purchase.
- Be cautious with watches originally sold in the United States, overseas imports, and devices that have changed ownership or been serviced.
- Confirm that the paired iPhone meets the software requirements.
If the app is missing, the Watch may be in an unsupported region, running incompatible software, paired with an incompatible iPhone, or using a model for which the feature is unavailable. A loose fit, motion, cold skin, tattoos, poor contact, or poor circulation can also cause an individual reading to fail.
What the feature measures—and what it does not
Blood oxygen estimates oxygen saturation, commonly expressed as SpO₂. It is a wellness feature, not a replacement for a clinical pulse oximeter, medical monitoring, or professional diagnosis. Readings can be affected by fit, movement, skin temperature, circulation, tattoos, and other conditions.
Do not use a single Apple Watch reading to make an emergency decision or diagnose a respiratory or cardiovascular condition. If you have symptoms, repeated concerning readings, or a known medical condition, seek appropriate medical advice.
Bottom line
The November 2024 trial concerned Masimo’s trade-secret allegations—not the ITC patent order that disabled blood oxygen on U.S. Apple Watches. Apple’s later workaround changed the practical situation: blood oxygen has reportedly returned to some eligible U.S. models, with the paired iPhone handling processing. Buyers and owners should verify the exact model, region, iPhone, and software rather than assuming that every Apple Watch now supports the feature.
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